Governments are running out of time to address climate change and to avoid the worst effects of rising temperatures, an influential UN panel warned yesterday.

Greater energy efficiency, renewable electricity sources and new technology to dump carbon dioxide underground can all help to reduce greenhouse gas emissions, the experts said. But there could be as little as eight years left to avoid a dangerous global average rise of 2C or more.

The warning came in a report from the Intergovernmental Panel on Climate Change (IPCC) published yesterday in Bangkok. It says most of the technology needed to stop climate change in its tracks already exists, but that governments must act quickly to force through changes across all sectors of society. Delays will make the problem more difficult, and more expensive.

Rajendra Pachauri, who chairs the IPCC, said the report would underpin negotiations to develop a new international treaty to regulate emissions to replace the Kyoto protocol when it expires in 2012.

The report said little on the best way to encourage greater take-up of cleaner technologies. A delegate present at the negotiations said the passages on international policy options had been watered down by the US, which is opposed to Kyoto-style agreements that rely on binding targets.

Harlan Watson, head of the US delegation, said the report "highlights the importance of a portfolio of clean energy technologies, consistent with our approach".

There were also rows about the role of nuclear power, with countries including Spain and Austria opposed to any form of words that endorsed an increase in electricity from nuclear technology.

David Miliband, the environment secretary, said: "Last year, the Stern review showed that we needed to act urgently to tackle climate change and that it was economically feasible to do so. The IPCC has confirmed that finding, and that we have access to the technology we need to take that action. We simply can't afford any other option but to act. That's why we're pushing hard for negotiations to start on a new global climate deal this year, and are working through the G8 group of nations and the UN climate change conference."

Yesterday's report follows two studies by the IPCC this year, which said unrestrained greenhouse gas emissions could drive global temperatures up as much as 6C by 2100, triggering a surge in ocean levels, destruction of vast numbers of species, economic devastation in tropical zones and mass human migrations.

The report said global emissions must peak by 2015 for the world to have any chance of limiting the expected temperature rise to 2C, which would still leave billions of people short of water by 2050.

Michael Roberts, of the Confederation of British Industry, said: "The report signals that there are barriers to realising the range of opportunities identified and that we all - consumers, businesses and governments - have a role to play in overcoming these obstacles. The debate now needs to be focused on action."

Hans Verolme, director of the WWF climate change programme, said: "The IPCC has delivered a road map for keeping the planet safe. Now it's the turn of politicians to do more than pay just lip service."